The present disclosure relates to a driving device for generating a rotational drive force for rotating a rotating body and an image forming apparatus provided with the same.
Conventionally, an electrophotographic image forming apparatus such as a copier, a printer or a facsimile machine forms a toner image on an image bearing member (e.g. photoconductive drum or transfer belt) by developing an electrostatic latent image formed on the image bearing member by supplying developer to the electrostatic latent image.
The image bearing member is involved in the formation of an electrostatic latent image, the development of the electrostatic latent image by toner and the transfer of a toner image. Thus, the image bearing member is required to have high rotation accuracy. Conventionally, a technique for reducing a driving speed by an endless metal belt mounted between pulleys having different diameters is known as a speed reducer arranged at an intermediate position of a transmission path for a rotational drive force from a drive motor to the image bearing member. Since there is no mesh between gears in such a technique, vibration associated with speed reduction is unlikely to be transmitted to the image bearing member.
Further, there is known a technique provided with an acoustic emission sensor for detecting an elastic wave, a transmitter for wirelessly transmitting a detection signal of the acoustic emission sensor by electromagnetic induction, and a discriminator for discriminating an abnormality. If an abnormality such as a crack occurs to a metal belt mounted between pulleys, an elastic wave of the metal belt detected by the sensor changes. The change of the elastic wave is analyzed by the discriminator and the abnormality is detected.
If the metal belt as described above moves in an axial direction on the pulley on which the metal belt is stretched or rotates in a state inclined with respect to the axial direction, it may cause a minute change in a speed reduction ratio. It is difficult to detect a minute behavior of the metal belt as described above with an abnormality detection technique based on a change of an elastic wave as described above.
The present disclosure was developed to solve the above problem and aims to detect a stretched state of a metal belt by a simple configuration.